Efficience de differentes strategies de detection de la Trypanosomiase Humaine Africaine aT. b. gambiense.

摘要

Resume Introduction La detection active de la Trypanosomiase Humaine Africaine (THA) se base souvent sur l'utilisation de deux tests de depistage: la palpation ganglionnaire (PG) et le card agglutination test for trypanosomiasis (CATT). Cette analyse de decision compare l'efficience de trois strategies alternatives pour ce depistage: PG seul, CATT seul ou leur combinaison en parallele (PG and CATT). Methode Une strategie de detection de THA a ete definie comme la sequence de l'etape de depistage suivi par la confirmation parasitologique. L'efficacite de chaque strategie a eteevaluee en nombre de vies sauvees. Le cout des tests de depistage et de confirmation a ete estime en USDollars . Les estimations des differents parametres proviennent de la litterature et des observations faites par le programme de controle de la THA en RD Congo entre 1996 et 2002. Une analyse de sensibilite a ete effectuee pour les parametres sujets a incertitude. Resultats La strategie basee sur le CATT revient a USDollars 125 par vie sauvee pour la sequence complete des tests, la PG revient a USDollars 517 et la combinee a USDollars 452. Le cout marginal de l'ajout du PG au CATT est entre 1225 a USDollars 5000 par vie sauvee. L'analyse de sensibilite montre que les resultats sont robustes aux variations plausibles des parametres. Discussion La strategie CATT est la plus efficiente des trois. L'efficacite en terme de vies sauvees d'aucune des strategies de detection ne depasse 60% des deces evitables. Cette faiblesse est due a la basse sensibilite des examens parasitologiques de confirmation. Un gain d'efficience dans le controle peut etre obtenu en recourant a la strategie CATT et en reinvestissant soit dans de meilleurs examens de confirmation, soit dans une plus grande couverture. Summary Introduction Population screening for human African trypanosomiasis (HAT) is often based on a combination of two screening tests: lymph node palpation (LN) and card agglutination test for trypanosomiasis (CATT). This decision analysis compared the efficiency of three alternative detection strategies: screening by LN only, CATT only and their combination (LN and CATT). Method An HAT detection strategy was defined as the sequence of screening and confirmation. Efficacy was evaluated in terms of lives saved. The cost of screening and confirmation tests was estimated in USDollars . The different parameters in the decision tree were based on published literature and observations of the HAT control programme in the Democratic Republic of Congo. A sensitivity analysis was carried out on those parameters subject to uncertainty. Results The cost-effectiveness of a detection strategy based on CATT was USDollars 125 per life saved, compared with USDollars 517 for LN and USDollars 452 for the combined. Marginal cost to add LN to CATT only was between USDollars 1225 and USDollars 5000 per life saved. Sensitivity analysis shows that these results are robust to variation. Discussion The CATT strategy was the most efficient. None of the strategies was able to avoid more than 60% of HAT deaths. This moderate efficacy is due to the low sensitivity of the confirmatory (diagnostic) tests. Substantial efficiency gains can be obtained by adopting a CATT only strategy and resources can be better allocated to more sensitive confirmatory tests or to increasing the coverage of populations at risk.